Propeller blade deicing means



Feb. 8, 1955 A. E. FELT 2,701,696

PROPELLER BLADE DEICING MEANS Filed May 14, 1951 "Ill/111111111111.

INVENTOR. Adolph Felt www? nA/LV AT TORNEY United States PatentPROPELLER BLADE DEICING MEANS Adolph E., Felt, Milwaukee, Wis., assignorto A. O. Smith Corporation, Milwaukee, Wis., a corporation of New Yorkcraft propeller blades and more particularly to a novel bulkheademployed within a hollow propeller blade to improve the de-icingcharacteristics thereof.

An object of the present invention is to provide a structurally simpleand economical method of de-icing a propeller blade, whereby a fluid,such as a hot gaseous medium, is directed through the hollow blade, tothe portion of the blade where the greatest ice formatlon is apt tooccur, by means of a rubber-coated glass fabric bulkhead.

Another object is to provide a lightweight durable bulkhead to seal allchambers except the leading edge chamber of a sectional propeller bladefrom the passage of hot gases therethrough, the bulkhead beingconstructed of a flexible material and adapted for interchangeable usein propeller blades of similar cross section.

A further object is to provide a bulkhead in a blade for directingde-icing fluids to the blade edge, which bulkhead is substantiallyflexible to absorb the breathing movement of the blade caused byresonant vibrations 1n the blade.

Still another object is to provide a novel means of attaching aheat-resistant fabric bulkhead to the inner surfaces of a hollowpropeller blade, whereby the cross sectional area of the blade wall isnot reduced by Saul attachment and hence the blade is not susceptible tofailure at the point of attachment during service.

The present invention is adapted for use with a hollow propeller bladecomprising a shank, into which the hot fluids, generally heated air orexhaust gases, are introduced, a tip, from which the gases are ejected,and a central section which extends between the shank and the tip, andthrough which the hot gases pass in the1r movement through the blade. Togive the blade added strength and rigidity, the central section has oneor more longitudinal webs joining its foil sections and forrnmg severallongitudinal passages or chambers, rather than a single chamber, and allor a number of these chambers may communicate with the shank dependingon the particular construction of the blade.

The present invention comprises a lightweight durable bulkhead, which isemployed to direct the hot gases from the shank, where they areintroduced into the blades, to the longitudinal chamber adjacent theleading edge of said blade by closing olf all other chambers whichcommunicate with the shank to the ow of said gases. The bulkhead ispreferably constructed of a flexible heatresistant fabric, such as glasscloth, coated with silicone rubber which is able to absorb the breathingmovements of the blade. This material is molded to the approximatecross-sectional contour of the chamber to be closed olf and securedthereto by vulcanizing, so that the blade will not be injured bychafling of the interior.

Thus, the heated air or exhaust gases which are introduced into theshank of the blades are directed, by virtue of the novel bulkhead, tothe chamber adjacent the leading edge of the blade, the portion of theblade subject to the most severe ice formation.

Gther objects and advantages of the present invention will appear in theaccompanying description of the embodirnents of the inventions.

ln the drawings:

Figure l is an elevational View of a propeller embodying the inventionwith parts being broken away and sectioned;

Fig. 2 is a transverse sectional view on the line 2--2 of Fig. l;

Fig. 3 is a fragmentary longitudinal section on the line 3-3 0f Fig. l;

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Fig. 4 is a view similar to Fig. l of a modified form of the invention;

Fig. 5 is a transverse section on line 5 5 of Fig. 4;

Fig. 6 is a fragmentary longitudinal sectionL on line 6 of Fig. 4;

Fig. 7 is a detail View of the bulkhead before assembly with thepropeller;

Fig. 8 is a fragmentary transverse sectional view of the propeller withthe bulkhead secured therein showing how the walls of the bulkhead adaptthemselves to the contour of the propeller wall; and

Fig. 9 is a fragmentary longitudinal section of the propeller showingthe bulkhead positioned ready to be vulcanized to the propeller wall.

Referring to the drawings, there is shown in Figs. l-3 an embodimentillustrating a typical propeller blade containing the present invention.The blade consists of a hollow shank 1, a hollow tip section 2, and acentral section 3, which extends between the shank and the tip sectionand comprises a tubular body section 4, to which is secured a leadingedge member 5 and a trailing edge member 6. Thus the central section 3is formed with three longitudinal passages or chambers, the trailingedge chamber 7, central chamber 8, and the leading edge chamber 9, allof which extend substantially the length of said section.

The root l0 of the tubular shank has a generally cylindrical shape. Theshank 1 flares outwardly from root liv to provide a generally flattercross-sectional shape in the portion thereof adjacent the centralsection 3. The shank is welded to central section 3 with the passage lllin the shank communicating with the central chamber 8 of said section.

The trailing edge member 6 is tapered inwardly toward shank 1 and closesoff chamber 7, there being no communication at the shank end of theblade between the trailing edge chamber 7 and either the central chamber8 or the shank passage 11.

The leading edge member 5 is similarly tapered inwardly toward shank land closes off chamber 9. However, an aperture l2 is formed in the wallof tubular body section 4 adjacent the shank permitting communicationbetween the leading edge chamber 9 and the central chamber 8 and shankpassage 11.

The portion of the central section 3, adjacent the tip 2, takes aflatter shape and is secured to said tip by suitable welding, thechambers 7, 8 and 9 communicating with the chamber 13 in said tip.

The tip 2 is formed with an aperture 14 in the upper flat portionthereof adjacent the trailing edge of the blade. The hot fluids whichare introduced into the blade through the shank l, are drawn throughaperture 14 to the atmosphere by the centrifugal action caused by bladerotation.

A flexible heat resistant bulkhead 15 is disposed within the tubularbody section 4 to prohibit the ow of the heated air or exhaust gasestherethrough.

The bulkhead 15 is preferably constructed of a glass fiber cloth whichis friction coated on both sides with silicone rubber. This material isextremely durable and is capable of withstanding the high temperaturesof the hot gases. The temperatures are generally in the range of 400-500F., and it is essential that the material employed will not burn or charat this heat.

Bulkhead 1S is of elongated trough-like shape, comprising a base 16 andside walls 17. The bulkhead is disposed within the tubular body section4 to the outboard or tip side of aperture 12, with the open top of saidbulkhead facing toward the shank of the blade, and the base 16, whichhas a generally elliptical shape substantially similar to thecross-section of bodysection 4, effectively closing off the inner end ofchamber 8 of section 4. The walls 17 of the bulkhead 1S extend from base16 toward the shank end of the blade to a position ontboardly adjacentthe aperture 12 and are in flexible engagement with the inner surfacesof section 4.

The walls 17 of the bulkhead are secured to the adjacent inner surfacesof section 4 by vulcanizing. This may be accomplished by interposing athin band of raw silicone rubber 18 between walls 17 and the bodysection 4 .adjacent the open end of the bulkhead, as shown in Fig. 9.

Heat is applied to the joint, and a suitable pressure means is utilizedwithin the blade to force the walls 17 against the inner surface oftubular section 4 to produce the desired vulcanization of bulkhead tosection d.

Thus, the bulkhead, while closing lolf the body section 4 to the ow ofgases, does not prevent the flow of gas from the shank through aperture12, and hence to the leading edge -chamber 9.

In operation, the heated air or exhaust gases are introduced into theshank 1 of the blade by a means, not shown, and pass through theaperture 12 to the leading edge chamber 9, the gases being preventedfrom passing through the tubular body section IlV by the bulkhead 15.The gases travel through chamber 9 to the tip chamber 13, where they aredrawn laterally across the t-ip of the blade to the aperture 14 bycentrifugal force caused by rotation of the blade.

There is shown in Figs. 4-6 another embodiment illustrating a typicalpropeller blade containing the present invention. The blade consists ofa tubular shank 19, a tip section anda hollow central section 21, whichextends between the shank and the tip. The central section 21 comprisesa leading edge member 22 and a trailing edge member 23, which areconnected by an upper foil plate 24 and a lower foil plate 2S. Areinforcing web 26 longitudinally divides the section 21 into a trailingedge chamber 27 and a leading edge chamber 28. The web 26 is securededgewise between the upper foil plate 24 and lower foil plate 25, andextends from the shank end of said section 21 to a slight distance shortof the tip end thereof, to provide a port 29 between the chamber 28 andthe chamber 27 at the tip 20.

The tubular shank 19 has a generally cylindrical shape at its root 30,and flares outwardly from said root to provide a generally attercross-sectional shape in the portion thereof adjacent to the centralsection 21. The shank 19 is welded to the section 21 with the passage 31in the shank communicating with both the leading edge chamber 28 and thetrailing edge chamber 27.

The portion of the central section 21 adjacent the tip 20 has agenerally flat shape and is welded thereto.

The trailing edge member 23 is formed with an aperture 32 in the portionthereof adjacent the tip, which serves as an exit for the hot gasesintroduced through the shank 19, and passing through leading edgechamber 2S and port 29.

A bulkhead 33, of similar construction to bulkhead 15 previouslydescribed in the rst embodiment, is employed to seal the trailing edgechamber 27 from the entry of the hot gases. The ow of the gases is thusrestricted to the leading edge chamber 2S producing a more effectivedeicing of the leading edge member 22.

The bulkhead 33 is of trough-like shape comprising a base 34 andoutwardly flared side walls 35. The bulkhead is disposed within thechamber 27 adjacent shank 19 of the blade with the open side facingtoward the shank, and having the base 34 effectively closing off thewedge-shaped chamber 27. The side walls 35 of the bulkhead are inyielding engagement with the inner surfaces of bottom foil plate 25,trailing edge member 23, top foil plate 24 and reinforcing member 26respectively.

Figure 7 shows the bulkhead as molded before attachment within theblade, and Figure 8 illustrates the same bulkhead disposed within thechamber 27, the exible nature of the bulkhead permitting it to conformto the rather irregular cross-sectional contour of said chamber.

The bulkhead .33 may be formed with a small vent hole 36 in the base 3dto facilitate the draining of any accumulation of oil, dirt, or similarundesirable matter.

The bulkhead 33 is attached within the blade preferably by vulcanizationin a manner similar to that previously set forth in the firstembodiment.

Due to Vresonant vibrations set up in a propeller blade such as byoperation of the engine and gears in the hub, passage of the blade pastthe wing of the plane, different air densities and certain maneuvers andthe like, the blade tends to breathe or expand and contract in service.The bulkhead provided by the invention is able to breathe with theblade. In addition, the manner of attachment of the bulkhead to theblade avoids chaing of the interior surface of the blade.

While the present invention has been described with respect to use withcertain ,particular propeller blades, it is understood that its use isnot limited thereto, but 'it may be employed with any type Vof hollow or'tubular-propeller blade into which hot gases may be introduced, todirect or delle'ct said gases to the portion of the blade mostsusceptible to ice formation.

Various embodiments of the invention are employed within the scope ofthe following claims.

I claim:

l. In a hollow propeller blade comprising shank and tip sections joinedby foil members having leading and trailing edge members, a heatresistant flexible nonmetallic bulkhead secured chordwise to the innersurfaces of the blade adjacent the shank and employed to direct hotilu-ids received from the shank to the leading edge portion of saidblade most susceptible to the formation of ice during service, saidbulkhead including a closed end having a periphery substantiallyconforming to the `chordwise cross section of the portion of the bladewherein the bulkhead is to be disposed and having side walls extendinginboardly from the periphery of said end and being disposed in lappingcontacting relation with the foil members and the trailing edge member,and a non-metallic bond securing the overlapping side Walls of 'thebulkhead to the blade members over which the bulkhead lies.

2. In a .hollow metal propeller blade adapted to pass hot gasestherethrough with the gases having a temperature in excess of 400 F. tode-ice the blade in service and said blade comprising shank and tipsections joined by foil members having leading and trailing yedgemembers, at least two chambers extending for substantially the length ofthe blade from the shank to the tip thereof with said chambers beingprovided by a longitudinally extending partition member joined t0 thefoil members of said blade, a bulkhead having a closed end with sidewalls extending inboardly from said end and having an open end oppositesaid closed end, said bulkhead disposed across the end of one of saidchambers adjacent the shank of the blade to direct hot gases receivedfrom the shank into the other of said chambers and along the leadingedge of the blade, said bulkhead being of flexible non-metallic materialand capable of withstanding the temperatures of the hot de-icing gaseswithout burning or charting, and said bulkhead having substantial depthwith the open end thereof facing the shank and the side Walls thereofoverlapping the foil members and the trailing edge member of said bladefor a substantial distance to cornpletely close off the chamber acrosswhich the bulkhead is secured, non-metallic means securing theoverlapping side walls of the bulkhead to the blade members over whichthe bulkhead lies, and means in said blade to discharge the hot gasestherefrom.

3. In a hollow metal propeller blade adapted to pass hot gasestherethrough with the gases being in the range of temperatures of about400 to 500 F. to fle-ice the blade in service and said blade comprisingshank and tip sections joined by foil members having leading andtrailing edge members, at least one partition member joined to the foilmembers `of the blade to provide the interior of the blade with at leasttwo longitudinally extending chambers, a bulkhead disposed across theend of one of said chambers adjacent the shank of the blade to directhot gases received 'from the shank into the other of said chambers andalong the leading edge of the blade, said bulkhead comprising an innerlayer of glass liber cloth coated with a durable rubber-like materialand capable of withstanding the temperatures of the hot de-icing gaseswithout burning or charring, and said bulkhead being of a deep drawnshape with the open end thereof facing the shank and the side wallsoverlapping the members of the blade for a substantial distance tocompletely close off the chamber across which the bulkhead is secured,vulcanizing means securing the overlapping side Walls of the bulkhead tothe blade members over which the bulkhead lies, and means in said bladeto discharge the hot gases therefrom.

References Cited in the lile of this patent UNITED STATES PATENTS1,937,966 Junkers Dec. 5, 1933 1,988,202 Hoover Jan. l5, 1935 2,470,128Barrick et al. May l 1949 2,522,955 Martin Sept. 19, 1950 2,541,661Palmatier et al. M Feb. 13, 1951 2,556,736 Palmatier June l2, 1951

